Loop type glow plug wires

[bgkast]

My new 1978 300D has a new set of loop type glow plugs that the previous owner installed, but the "toaster" type wires that run between them are missing. Will it be OK to use thick gauge standard wire to connect the plugs, or does somebody have a spare set of the stock wires left over from upgrading to pencil type plugs?


Thank you.

[barry123400]

You have pulled a plug to make sure they are the loop plugs with an open filament? There are conversion plugs that look simular I think.
If they are the loop series plugs get the connecting wires from a wrecker or wherever if the last owner cannot give them to you. Their resistance will be critical in division of the voltage properly down the chain.
Straight wire I believe may burn out the plugs as the series plugs are very low actual voltage with a substantial drop on the external squigly wires. Thats why the wires glow in the dark when the circuit is activated. Also check the plugs for continuity before hooking them back up. Just in case someone else did something strange already and toasted one or more.
The series plugs are designed at .8volt or 1.2 volt apiece. I do not remember. So one way or another the plugs operating voltage in total is either 3.2v or 4.8 volt on a four cylinder.
The rest of the twelve volts is dropped across the connecting wires. Now here is where one might have to be a little careful. In theory the resistance of the wires for the five cylinder older design could be different than for the older four cylinder engine.

[vstech]

does the plug have a simple short brass connector and wire between the plugs, or are there theese:

in there? is the plug system open?
check Diesel Giant's site for the loop upgrade directions and see if it matches what you have....
http://www.dieselgiant.com/mercedesdieselloopglowplugrepair.htm
if you have loop plugs in there, the stud that the wire hooks to will be like 1" or so long from the base of the injector nut to the end of the stud... the converted pencil type are only like 3/8" long.

Originally Posted by bgkast

Will it be OK to use thick gauge standard wire to connect the plugs

No, the toaster wires are resistor wires. Without them the plugs will see too much voltage and suffer an early demise.

[Johnhef]

If it still has the loop plugs, just get the pencil style upgrade, its only about $100 or so and well worth it! I bought mine from http://www.alloemautoparts.com you may have to email them and ask about the kit, I don't remember how I found it on their page before. Comes with glow plugs, wires and new relay unit.

[kerry]

All you need are the plugs. No need to switch out the relay. I wouldn't bother with trying to fix loop plugs.

[bgkast]

Originally Posted by ForcedInduction

No, the toaster wires are resistor wires. Without them the plugs will see too much voltage and suffer an early demise.

That's what I figured.

I did pull a plug and it seems the previous owner installed 5 new loop type plugs. I think I will track down the correct wires and use the loop plugs for now since they are new.

[vstech]

I have two or three full sets if you need them... PM me.